NOTIFICATION OF MAJOR INTERESTS IN SHARES



1. Name of listed company

SPIRENT COMMUNICATIONS PLC


2. Name of shareholder with a major interest

LEXA B.V.


3. Please state whether notification indicates that regarding the holding of the
shareholder named in 2 above; in respect of a non-beneficial interest; or in the
case of an individual holder if it is a holding of that person's spouse or
children under the age of 18

IN RESPECT OF THE BENEFICIAL HOLDING OF LEXA B.V.


4. Name of the registered holder(s) and, if more than one holder, the number of
shares held by each of them

LEXA B.V.


5. Number of shares / amount of stock acquired

N/A


6. Percentage of issued class (any treasury shares held by the listed company
should not be taken into account when calculating percentage)

N/A


7. Number of shares / amount of stock disposed

N/A


8. Percentage of issued class (any treasury shares held by the listed company
should not be taken into account when calculating percentage)

N/A


9. Class of security

ORDINARY SHARES OF 3 & 1/3 PENCE EACH


10. Date of transaction

30 AUGUST 2006 (SEE ADDITIONAL INFORMATION)


11. Date company informed

30 AUGUST 2006


12. Total holding following this notification

120,000,000 ORDINARY SHARES


13. Total percentage holding of issued class following this notification (any
treasury shares held by the listed company should not be taken into account when
calculating percentage)

13.03%


14. Any additional information

SPIRENT COMMUNICATION PLC IS CURRENTLY OPERATING A SHARE BUY BACK PROGRAMME AND
AS AT 30 AUGUST 2006 HAD PURCHASED 50,990,000 SPIRENT COMMUNICATIONS PLC
ORDINARY SHARES OF 3&1/3 PENCE INTO TREASURY OUT OF A TOTAL ISSUED SHARE CAPITAL
OF 971,934,304 SHARES.  AS SHARES HELD IN TREASURY ARE NOT INCLUDED IN THE
CALCULATION OF HOLDINGS OF MAJOR SHAREHOLDERS A CONSEQUENCE OF THE BUY-BACK
PROGRAMME HAS BEEN THAT THE PERCENTAGE HOLDING OF LEXA B.V. HAS INCREASED FROM
12.4% OF THE ISSUED SHARE CAPITAL TO 13.03% OF THE ISSUED SHARE CAPITAL,
ALTHOUGH THE ACTUAL NUMBER OF SHARES HELD OF 120,000,000 REMAINS UNCHANGED.


15. Name of contact and telephone number for queries

WARREN NASH - 01293 767676


16. Name and signature of duly authorised company official of the listed company
responsible for making this notification

WARREN NASH


Date of notification

31 AUGUST 2006




                      This information is provided by RNS
            The company news service from the London Stock Exchange
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